[improvement] Update Signal onboarding to include link to connect to Signal

[mattwr18]

As a contributor
I would like to have a one click solution to finding the signal user from the server
So that I don't need to manually search by phone number, etc.

We can set the username of the signal server phone number with

signal-cli --config /home/.local/share/signal-cli updateAccount -u <USERNAME>

This will return the username with deliminator display_name.000 and a link that can be used to connect the contributors.